Thermostatic switch



APFE 24, 1951 1 |=.y L.. DARUNG 25509188 THERMOSTATIC SWITCH Filed March 27, 1950 Fig. 9;

W zum En @72 @Tij ATTOR N EY Patented Apr. 24, 1951 THERMOSTATIC SWITCH Frank Lee Darling, Los Angeles, Calif., assignor to D. K. M. Company, Los Angeles, Calif., a corporation of California Application March 27, 1950, Serial No. 152,065

9 Claims.

My invention has for an object to provide a thermostatic circuit opener and closer `which is especially adapted to use on airplanes, and particularly those that fly at high altitudes.

Another object is to provide a thermostatic circuit switch which will be very sensitive and will remain so over a long period of time.

Other objects will in part be obvious and in part will be pointed out hereinafter.

To the attainment oi the aforesaid objects and ends invention still further resides in the novel details of construction, combination and arrangement of parts, all of which will be rst fully described in the following detailed description, and then be particularly pointed out in the appended claims, reference being had to the accompanying drawing in which:

Fig. 1 is a top plan view of one embodiment of my invention.

Fig. 2 is a vertical section on the line 2-2 of Fig. 1.

Fig. 3 is a cross Section on the line 3-3 of Fig. 2.

Fig. 4 is a cross section on the line 4-4 of Fig. 2.

Fig. 5 is a top plan View of a second embodiment of the invention.

Fig. 6 is a vertical section on the line 6 6 of Fig. 5.

Fig. '7 is a cross section on the line I-I of Fig. 6.

' Fig. 8 is a detail inverted plan view of the rodguiding plug.

Fig. 9 is a detail View hereinafter specifically referred to.

In the drawing, in which like numerals of refl erence indicate like parts in all the gures, I represents a cylindrical metallic casing securely Welded or otherwise secured air-tight to a base disc 3 which has holes 3a for receiving suitable securing screws (not shown) for fastening the device to the structure to be protected. The casing I is provided at its top with a neck 2 through which a metallic binding post 6 projects, and over which a cap 4 of porcelain or other suitable insulation material is fitted.

Within the casing I the binding post has a flange 1 and a split support or adjustable-contact-holder 8. The holder 8 has threaded portions 9 to receive and hold, with retaining friction, an adjustable contact set screw I0.

. Within the neck 2 and surrounding the binding post 6 is an insulating and sealing packing 5 composed, preferably, of bre glass with lacquer insulation, and between the kflange 'I and the top of the casing is interposed a mica washer II, the parts being drawn tightly together by a nut I1 threaded on post 6. The flange I is further sealed air-tight from the casing I by means of a suitable sealing material I2 which is owed into place under a high temperature. The materials 5, II, and I2 not only insulate the binding post from the casing, but they also prevent the instrument from breathing :from low to high altitudes and vice versa, a fault possessed by those thermostatic switches now in use. When a ship ies from sea level to 40,000 feet elevation there is a change of internal pressure on the device of about seven pounds, and after several flights if the casing of the device leaks air, foreign material is breathed in and out of the casing, which has a tendency to fog the contact points and thereby cause failure of operation should a fire really exist or occur.

The casing I is also provided with an internally threaded boss I5 normally closed air-tight by a screw plug I6. The boss I5, if desired, may have a bore large enough to permit removal or placement of contact screw I0. Screw I0 has a socket Illa to receive an Allen wrench for an obvious purpose. The casing I is further provided with an internally threaded boss I3 to receive a closure plug I4 and one end of a spring I9.

In the rst embodiment of my invention I8 represents a bell-crank lever whose short arm 2I lies in the slot 25 of a plug 24, the lever being pivoted, as at 22, and carrying a contact point 20. The spring I9 constantly urges the lever I8 toward contact I 0.

Welded or otherwise secured to a flange 28 of the base 3 is an expansible and contractable tube 21 whose lower end is plugged, as at 30, which is silver soldered in place and is also held by crimping at 3I. A rod 29 is securely anchored to the plug 30 at one end and has a ball 32 swaged into its other end. The rod is guided in the bore 26 of the plug 24 in the slot 25 of which the lever I8 is mounted, as above described.

Fig. 2 shows the normal or circuit-open position of the parts.

The embodiment of Figs. 5 and 6 differs from that of Figs. 1 to 4 inclusive in that the lever |83 is normally held in closed-circuit position, i. e.,v

with contacts I0 and 20 engaged. Also the short arm 2IaY of the lever is slotted at 23 and the rod 29a passes through the slot and carries a cross pin 32a inr its end 33. The pin 32a engages the top of the arm -2Ia and the arm 2|la is pivoted near its free end to the plug, as` at 22a.

Operation In the embodiment of Figs. 1 to 4, inclusive, when tube 21 warms up its expands at a greater rate than does the rod 29, thereby lowering the ball 32 and permitting spring I9 to move lever I8 to close a circuit through points IIJ and 20,'

thereby giving a suitable signal or warning. In the form shown in Figs. 6 and 7, when tube 21 expands pin 33 will pull down and rock lever I8a to separate contacts I0 and 2U.

The first embodiment is for an open-circuit alarm system; while the second embodiment is for use in a closed-circuit system. In either case as tube 21 contracts spring I9 will restore the contacts to their normal positions.

By removing screw plug I6 an Allen wrench may be inserted into the socket II)a of contact Screw I0 and the position of the conta-cts can be adjusted as required.

Since the operative connections between the rods 29, 29?- and their respective levers I8, I8a are constantly held in contact, there is no wear from vibration as all slack is taken up and wear is eliminated by the constant pressure of spring I9.

By virtue oi the peculiar connection between the rod 29a and lever I8a, should the instrument be subjected to extremely low temperatures, rod 29a will continue to rise when tube 21 contracts without putting any strain on the movable parts because of rapid temperature changes. Tests have shown that this instrument will operate successfully in temperatures as low as 90 below zero.

From the foregoing description, taken in connection with the accompanying drawing, it is thought that the construction, operation and advantages of the invention will be clear to those skilled in the art to which it relates.

What I claim is:

1. In a thermostatic switch, a casing, a base integral with said casing, said casing having a neck, a metal binding post mounted in and insulated from said casing and having a portion projected through said neck, means securing said binding post in place, said binding post having a contact holder, a contact adjustably mounted in said holder, said casing having an internally threaded boss in alignment with the aforesaid contact, a

closure plug for said boss, a lever pivotally mounted in said casing and having a contact element for engaging said rst mentioned Contact, means continuously tending to move said lever to circuit-closing position, and thermostatic means acting on said lever in opposition to said continuously tending means.

2. In a thermostatic switch, a casing, a base integral with said casing, said casing having a neck, a metal binding post mounted in and insulated rom said casing and having a portion projected through said neck, means securing said binding post in place, said binding post having a contact holder, a contact adjustably mounted in said holder, said casing having an internally threaded boss in alignment with the aforesaid contact, a closure plug for said boss, a lever pivotally mounted in said casing and having a contact element for engaging said first mentioned contact, means continuously tending to move said lever to circuit-closing position, and thermostatic means acting on said lever in opposition to said continuously tending means, said continuously tending means comprising a spring one end of which engages said lever, said cas- 75 for securing said binding post to said casing,

4 ing having a tubular boss into which the other end of said spring is seated.

3. In a thermostatic switch, a casing, a base integral with said casing, said casing having a neck, a metal binding post mounted in and insulated from said casing and having a portion projected through said neck, means securing said binding post in place, said binding post having a contact helder, a contact adjustably mounted in said holder, said casing having an internally threaded boss in alignment with the aforesaid contact, a closure plug for said boss, a lever pivotally mounted in said casing and having a contact element for engaging said rst mentioned contact, means continuously tending to move said lever to circuit-closing position, thermostatic means acting on said lever in opposition to said continuously tending means, said continuously tending means comprising a spring one end of which engages said lever, said casing having a tubular boss into which the other end of said spring is seated, and a Screw plug threaded into said tubular boss for adjusting the force of said spring.

4. In a thermostatic circuit make and break device, a casing having a neck at the top, a mounting element on which the other end of the casing is fixedly and air-tightly secured, a binding post comprising a disc portion, a threaded rod portion and a contact holder, said rod portion projecting through said neck, insulation and sealing material in said neck and encircling said rod portion, a dielectric washer between said disc portion and the top of said casing, an insulating cap on said neck, a nut on said rod-like portion for securing said binding post to said casing, a contact element carried by said contact holder, a lever pivotally mounted in said casing and having a contact element disposed in cooperative relation to said first mentioned contact element,

spring means acting on said lever in one direction, and thermostatic means acting on said lever in the opposite direction.

5. In a thermostatic circuit make and break device, a casing having a neck at the top, a mounting element on which the other end of the casing is lxedly and air-tightly secured, a binding post comprising a disc portion, a threaded rod portion and a split contact holder, said rod portion projecting through said neck, insulation and sealing material in said neck and encircling said rod portion, a dielectric washer between said disc portion and the top of said casing, an insulating cap on said neck, a nut on said rod-like portion for securing said binding post to said casing, a contact element carried by said contact holder in threaded engagement with the same, a lever pivotally mounted in said casing and having a contact element disposed in cooperative relation to said rst mentioned contact element, spring means acting on said lever in one direction and thermostatic means acting on said lever in the opposite direction.

6. In a thermostatic circuit make and break device, a casing havinga neck at the top, a mounting element on which the other end of the casing' is iixedly and air-tightly secured, a binding post comprising a disc portion, a threaded rod portion and a contact holder, said rod portion projecting through said neck, insulation and sealing material in said neck and encircling said rod portion, a dielectric washer between said disc portion and the top of said casing, an insulating cap on said neck, a nut on said rod-like portion a contact element carried by said contact holder, a lever pivotally mounted in said casing and having a contact element disposed in cooperative relation to said rst mentioned contact element, spring means acting on said lever in one direction, thermostatic means acting on said lever in the opposite direction, said thermostatic means comprising an expansible tube one end of which is secured to said mounting element, a rod in said tube one end of which rod is secured to the free end of said tube, and a rod guide in the other end of said tube through which said rod projects, said rod having an operative connection to said lever.

7. In a thermostatic circuit make and break device, a casing having a neck at the top, a mounting element on which the other end of the casing is Xedly and air-tightly secured, a binding post comprising a disc portion, a threaded rod portion and a contact holder, said rod portion projecting through said neck, insulation and sealing material in said neck and encircling said rod portion, a dielectric washer between said disc portion and the top of said casing, an insulating cap on said neck, a nut on said rod-like portion for securing said binding post to said casing, a contact element carried by said contact holder, a lever pivotally mounted in said casing and having a contact element disposed in cooperative relation to said first mentioned contact element, spring means acting on said lever in one direction, and thermostatic means acting on said lever in the opposite direction, said casing having oppositely disposed internally threaded bosses in alignment with said contact elements, screw plugs in said bosses, one of said bosses serving in part as a socket for said spring means.

8. In a thermostatic circuit make and break device, a casing having a neck at the top, a mounting element on which the other end of the casing is xedly and air-tightly secured, a binding post comprising a disc portion, a threaded rod portion and a contact holder, said rod portion projecting through said neck, insulation and sealing material in said neck and-encircling said rod portion, a dielectric washer between said disc portion and the top of said casing, an insulating cap on said neck, a nut on said rod-like portion for securing said binding post to said casing, a contact element carried by said contact holder, a lever pivotally mounted in said casing and having a contact element disposed in cooperative relation to said first mentioned contact element, spring means acting on said lever in one direction, and thermostatic means acting on said lever in the opposite direction, said casing having oppositely disposed internally threaded bosses in alignment with said contact elements, screw plugs in said bosses, one of said bosses serving in part as a socket for said spring means, and the other of said bosses being of greater internal diameter than the external diameter of said rst mentioned contact element.

9. In a thermostatic circuit make and break device, a casing having a neck at the top, a mounting element on which the other end of the casing is xedly and air-tightly secured, a binding post comprising a disc portion, a threaded rod portion and a contact holder, said rod portion projecting through said neck, insulation and sealing material in said neck and encircling said rod portion, a dielectric washer between said disc portion and the top of said casing, an insulating cap on said neck, a nut on said rod-like portion for securing said binding post to said casing, a contact element carried by said contact holder, a lever pivotally mounted in said casing and having a contact element disposed in cooperative relation to said i'irst mentioned contact element, spring means acting on said lever in one direction, thermostatic means acting on said lever in the opposite direction, said thermostatic means comprising an expansible tube one end of which is secured to said mounting element, a rod in said tube one end of which rod is secured to the free end of said tube, and a rod guide in the other end of said tube through which said rod projects, said rod having an operative connection to said lever, said rod guide having a slot to receive one leg of said lever and to which guide said lever is pivoted.

FRANK LEE DARLING.

No references cited. 

